package org.apache.solr.search.grouping.distributed.shardresultserializer;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.search.Sort;
import org.apache.solr.common.util.NamedList;

import java.io.IOException;

/**
 * A <code>ShardResultTransformer</code> is responsible for transforming a
 * grouped shard result into group related structures (such as
 * {@link org.apache.lucene.search.grouping.TopGroups} and
 * {@link org.apache.lucene.search.grouping.SearchGroup}) and visa versa.
 * 
 * @lucene.experimental
 */
public interface ShardResultTransformer<T, R> {

	/**
	 * Transforms data to a {@link NamedList} structure for serialization
	 * purposes.
	 * 
	 * @param data
	 *            The data to be transformed
	 * @return {@link NamedList} structure
	 * @throws IOException
	 *             If I/O related errors occur during transforming
	 */
	NamedList transform(T data) throws IOException;

	/**
	 * Transforms the specified shard response into native structures.
	 * 
	 * @param shardResponse
	 *            The shard response containing data in a {@link NamedList}
	 *            structure
	 * @param groupSort
	 *            The group sort
	 * @param sortWithinGroup
	 *            The sort inside a group
	 * @param shard
	 *            The shard address where the response originated from
	 * @return native structure of the data
	 * @throws IOException
	 *             If I/O related errors occur during transforming
	 */
	R transformToNative(NamedList<NamedList> shardResponse, Sort groupSort,
			Sort sortWithinGroup, String shard) throws IOException;

}
